The present invention relates to a gasket for a fuel battery which is used as a seal portion in the fuel battery.
About 100 to 400 sheets of separators (current collecting plates) are used in a stack for the fuel battery in correspondence to a number of lamination of unit cells. At this time, there are a case of simply laminating the cells so as to form the stack and a case of laminating modules, one unit of which is formed by a plurality of the cells, so as to form the stack. In the fuel battery stack mentioned above, in the case that the cell or the module does not normally operate, a reduction of a power generating efficiency, an abnormality or a trouble is caused. However, in the stack state, it has not been easily known which of the cells or modules generates a problem. For example, in the case that a voltage drop or a current reduction is generated due to a defect of the separator, a problem of an electrode, an abnormality of a fuel gas concentration, an abnormality of an electrolyte membrane or the like, it has been conventionally unknown which of the cells or modules the voltage drop or the current reduction is generated in. Accordingly, under the present circumstances, the stack is dissembled and the cells or the modules are checked by a tester one by one.
The present invention is made by taking the matters mentioned above into consideration, and an object of the present invention is to provide a gasket for a fuel battery which is provided with a function capable of performing an operation of specifying a cell or a module generating a voltage drop or a current reduction without disassembling a stack for a fuel battery, by directly measuring a voltage or a current of the cell or the module by a print circuit being electrically in contact with a separator, an a function of taking out an output of a gas sensor or a temperature sensor built in the cell or the module.
In order to achieve the object mentioned above, in accordance with a first aspect of the present invention, there is provided a gasket for a fuel battery characterized in that gaskets are provided on both surfaces of a print circuit for taking out an electric signal within a cell or a module.
Further, in accordance with a second aspect of the present invention, there is provided a gasket for a fuel battery as recited in the first aspect mentioned above, characterized in that the print circuit is a flexible print circuit.
Further, in accordance with a fifth aspect of the present invention, there is provided a gasket for a fuel battery characterized in that a detecting portion having a function of taking out an output of a gas sensor built in a cell or a module is integrally assembled.
Further, in accordance with a fourth aspect of the present invention, there is provided a gasket for a fuel battery as recited in the third aspect mentioned above, characterized in that the gasket has a substrate mounted to an electrolyte membrane of a reaction electrode portion, a flexible print circuit lapped over the substrate, an electrode provided in the flexible print circuit and being in contact with the separator, and a gasket fixed to the substrate and holding the flexible print circuit between the gasket and the substrate.
Further, in accordance with a fifth aspect of the present invention, there is provided a gasket for a fuel battery characterized in that a detecting portion having a function of taking out an output of a gas sensor build in a cell or a module is integrally assembled.
Further, in accordance with a sixth aspect of the present invention, there is provided a gasket for a fuel battery characterized in that a detecting portion having a function of taking out an output of a temperature sensor build in a cell or a module is integrally assembled.
Further, in accordance with a seventh aspect of the present invention, there is provided a gasket for a fuel battery characterized in that a signal line for taking out an electric signal within a cell or a module is integrally formed with a gasket substrate in accordance with a printing method or an etching method, and a gasket is integrally formed with the substrate.
Further, in accordance with an eighth aspect of the present invention, there is provided a gasket for a fuel battery as recited in the seventh aspect mentioned above, characterized in that the signal line takes out an electric signal of a current application diagnosis, a temperature, a gas or the like.
Further, in accordance with a ninth aspect of the present invention, there is provided a gasket for a fuel battery as recited in the seventh aspect mentioned above, characterized in that the gasket is formed in a double structure, the signal line is arranged between the gaskets, and an electrode is also arranged there.
Further, in accordance with a tenth aspect of the present invention, there is provided a gasket for a fuel battery as recited in any one of the first to ninth aspects mentioned above, characterized in that a front surface of a circuit formed in the substrate is coated with a protecting member constituted of an insulating membrane.
By measuring the voltage or the current between the separators at the print circuit terminal in a stack state formed by laminating a plurality of cells in which the gasket for the fuel battery with the print circuit in accordance with the present invention provided with the structure mentioned above is built, or by taking out the sensor output, it is possible to check only on connecting a tester to the detecting portion without dissembling the stack. As a particular structure of the detecting portion and the gasket, as described in the third aspect, it is preferable to have a substrate mounted to an electrolyte membrane of a reaction electrode portion, a flexible print circuit lapped over the substrate, an electrode provided in the flexible print circuit and being in contact with the separator, and a gasket fixed to the substrate and holding the flexible print circuit between the gasket and the substrate. The circuit portion may be formed by directly adhering a metal foil to the substrate or printing a conductive ink. Further, the present invention is structured such that the gasket for the fuel battery having the gaskets on both surfaces of the print circuit for taking out the electric signal within the cell or the module is held between the separators, and the electric signal take-out portion for taking out the electric signal (the voltage, the current or the like) is integrally assembled with the seal.
Further, as the gasket for a fuel battery in accordance with the sixth aspect of the present invention provided with the structure mentioned above, in the case that the signal line for taking out the electric signal within the cell or the module is integrally formed with the gasket substrate in accordance with the printing method or the etching method, an occupying space is hardly expanded in comparison with the structure having no signal line, so that it is possible to provide the gasket which saves space and has an excellent practicability in this view.
In this case, the following technical matters are included in the present application.
(1) That is, at first, in order to achieve the object mentioned above, one gasket proposed by the present application is a gasket with a print circuit used in the stack for the fuel battery. When the print circuit is the flexible print circuit, it is advantageous to make the structure thin.
(2) Further, the substrate is made of a heat-resistant resin sheet such as a polyimide (PI), a polyether nitrile (PEN), a polyethylene terephthalate (PET), an epoxy-based resin, a phenol-based resin or the like, and the circuit portion is formed by using a conductive ink, a copper, a nickel, a stainless steel, a titanium, a tungsten, a gold, a Permalloy, a Nichrome, an aluminum foil or the like. In this case, the metal foil or the like such as the copper or the aluminum which is easily corroded by an electrolyte solution or the like can be covered by a metal having a corrosion resistance, an alloy thereof, a metallic compound or a coating material. Next, the gasket is arranged in the print circuit substrate so as to constitute the seal member. The arrangement is executed by a method of using an adhesive agent at a time of forming the gasket, a method of arranging on the basis of an adhesive property of the seal member itself, or a method of arranging after forming the seal member. In this case, the seal member is made of a saturated rubber such as a silicone rubber, a fluoro silicone rubber, an ethylene propylene rubber, a fluorine-contained rubber, a butyl rubber, a hydrogenation isoprene rubber, a hydrogenation butadiene rubber, a hydrogenation styrene butadiene rubber, a hydrogenation styrene isoprene rubber, an acrylic rubber, an ethylene acrylic rubber, a fluoro acrylic rubber, a styrene-based rubber, a hydrogenation styrene isoprene rubber and the like, or a liquid rubber thereof, a block type thermoplastic elastomer such as a styrene-butadiene styrene block copolymer, a styrene-isoprene styrene block copolymer and the like or a thermoplastic elastomer obtained by hydrogenating an unsaturated bonding portion thereof, a thermoplastic elastomer such as a polyester-base thermoplastic elastomer, an olefin-based elastomer and the like. In this case, when the seal member has an adhesive property to a circuit board, it is possible to fix the gasket to the circuit board without using the adhesive agent, so that this structure is preferable. A self-adhesive gasket mentioned above can be satisfied by introducing a functional group, for example, a carboxyl group, a hydroxyl group, a ketone or an imide to a part of a chemical structure of the seal member or blending an adhesive agent component to the seal member. In this case, since the adhesive property has a preferable combination in correspondence to the natures of the seal member and the circuit board, it may be suitably selected. Further, a seal member which is selectively adhered only to the substrate without being adhered to a molding die, that is, a seal member having a selective adhesion property is more preferable. For example, a selective adhesive silicone rubber or the like can be listed tip. In this case, on the front surface of the circuit formed in the substrate, it is possible to cover all the front surface except a circuit portion or a terminal front end portion by a protecting member as occasion demands. The protecting member may be any material forming an insulative membrane, however, normally a material similar to the substrate or selected from materials having a good adhesive property with respect to the seal member is used. When using a polyethylene terephthalate having a small coefficient of permeability for the gas and the liquid, that is, having an excellent sealing property for the circuit board, and using a member having the same property as the polyethylene terephthalate for the coating member, the substrate and the coating member are firmly bonded due to a thermo compression bonding, so that the electrolyte solution or the like is hard to permeate into the circuit portion, and in addition to a corrosion preventing effect in the circuit portion of the circuit board between the circuit board and the coating member, it is possible to expect an effect capable of preventing a warp due to a difference of thermal expansion between the substrate portion and the circuit portion. Further, the materials is not necessarily of same kind and different kinds of materials may be employed, as far as there is an affinity between the substrate material and the coating material.
(3) Both of the structures (1) and (2) mentioned above are the gasket arranged between the separators, and the print circuit is used for the purpose of detecting the voltage or the current of the separator.
(4) By placing the electrode for the purpose of checking a change of the voltage or the current of the separator, and the print circuit for the purpose of outputting the signal from the electrode, in the gasket used between the separators, the structure is made such that it is possible to check which of the cells or modules the voltage drop or the current reduction is generated in, from the external portion.
(5) Accordingly, it is possible to check the problem without dissembling the stack by checking the print circuit with respect to which of the cells has become abnormal in a state of the stack assembly.
(6) The fifth aspect mentioned above makes it possible to measure a concentration of hydrogen supplied to the cell for the fuel battery from an external portion of the cell, by using a sensor for measuring the concentration.
(7) Further, the sixth aspect mentioned above makes it possible to measure a temperature of an inner portion of the cell for the fuel battery froman external portion of the cell, by using a sensor for measuring the temperature.
Further, in connection with the inventions as recited in the seventh to ninth aspects mentioned above, the following technical matters are included in the present application.
(8) That is, in order to achieve the object mentioned above, one gasket proposed by the present application is a cell seal for a fuel battery, a signal line is integrally formed in a frame of the cell seal in accordance with a printing or the like, by a gasket being integrally formed with a signal line for taking out an electric signal within the cell.
(9) Further, in a cell seal for a fuel battery, a signal line is integrally formed in a frame of the cell seal in accordance with a printing or the like, by a gasket being integrally formed with a signal line for taking out an electric signal within the cell, and at least one signal line is provided.
(10) Further, in the seal recited in the item (8) mentioned above, the seal is provided for the purpose of takingout anelectric signal of a current application diagnosis, a temperature, a gas or the like.
(11) Further, in the seal recited in the item (8) mentioned above, beads of the cell seal are made in a double structure, the signal line is arranged between the beads, and the electrode is arranged.
(12) Further, in the case of using the cell seal obtained by forming the seal in the frame of the resin or the like, the structure is characterized that the signal line is arranged in the frame in accordance with a printing, an etching or the like and the seal is integrally formed in the frame in which the signal line and the resin frame are integrally formed, whereby even in the case of having the signal line, it is possible to secure the same space and assembling property as those of the seal having no signal line, and a cost increase can be restricted only to that for printing the signal line.
(13) Further, not only the electric signal for the voltage, the current or the like, but also signal lines for a hydrogen gas sensor and a temperature sensor are arranged in parallel orby use, whereby the structure can comply with respective needs.
(14) As an embodiment, a sheet in which a pressure sensitive heat sensitive adhesive agent (PSA: silicone based) is applied to the structure obtained by printing the carbon electrode and the signal line on the PET film and mold release paper attached thereto is produced, and is punched in a frame shape by a punching mold, followed forming a selective adhesive silicone rubber (SHINETSU CHEMICAL CO., LTD: X-34-1277A/B) by a liquid injection molding machine. The product is called a frame type (or carrier type) cell seal, is attached to the MEA in which the electrode is mounted to an ion exchange membrane after peeling the mold release paper in the frame type seal and is thereafter mounted by applying a heat and a pressure. In the case of assembling in the cell, it is possible to monitor a current application state of the GDL by assembling so as to align with the GDL.
(15) Further, as another embodiment, in the structure mentioned above, by making the cell seal portion in the double bead shape, the signal line is arranged between the beads, and further the electrode is arranged so as to be in contact with the signal line. The electrode is made of a conductive material such as a conductive rubber, a carbon or the like.
(16) In accordance with the structure mentioned above, since the signal line is printed in the frame for the purpose of mounting the seal to the ion exchange membrane, the space is not expanded and man hours for assembling can be reduced, so that it is possible to produce with only a cost increase corresponding to the signal line printing cost, in comparison with the cell seal having no signal line for the diagnosis monitor.